I am currently having an issue with someone I know in that every time we debate about a single item, and he knows that he's wrong, he will turn it into a kind of broad-spectrum topic and then we start debating metaphysics or something completely unrelated to the original topic. He's taken philosophy and I haven't and I feel unequipped to counter his points when I know that I made a pretty established argument. It's driving me nuts.
For example, i'll say that subject "A" is a fact and has been proven by science (gravity for example). To me, the existence of gravity is a hard fact and demonstrable. However, he'll counter with something like "well it's only a fact to what humans can percieve, there's nothing that says the next time I throw a ball in the air it won't keep going up."
The problem I'm having is, well, I have to concede it's true; that is incredibly unlikely but he just ruined my argument that gravity is a fact by basically saying that in the vastness of the universe and how we can't predict everything and haven't seen EVERYTHING it's not %100. It's 99.99999%. so he uses that little bit as leverage, then dismisses it as subject to human error.
Basically he relies heavily on the idea that humans are ignorant and he thinks it's silly that scientists claim to know things when none of it is absolutely 100% which is true, that there is so much out there in the universe and reality that it's foolish to predict things, we can NEVER know everything and we never will, so to him absolutely everything falls under the label of "only applies as humans percieve it" opening the argument up to the idea that there are different sciences and maths out there and ways of doing things completely unknown to us and unlike anything on earth which again COULD be possible.
My stance is that science does and can prove things, and that the wild assertions like his are a) not useful to guess at, and b) so unlikely that it's absurd to suggest otherwise based on hard evidence and c) that since I am a human and I care about humanity I value the perspective of humans more than anything else because it applies directly to me and my entire race--AKA the only percievers that matter at this time. But he keeps making these crazy refutations of again for example somehting as solid as gravity, and then basically says that humans are too stupid to know anything for sure and because of that he doesn't have to accept that gravity exists.
Can someone please explain to me what the technical terms are for our opposing views? And perhaps link me some methods that I can use ammunition agaisnt his mode of thought? I'm not stupid enough to completely dismiss his idea but it's just too unlikely and not a useful way of thinking to me. I honestly think he uses this as a sort of scapegoat to get out of conceding to my arguments which is not fair. I heard it's called epistomology or something like that? Basically I'm more of the "there are established truths" mode of thought. Like I claim to know that 2+2=4 but then rather than jsut agreeing he'll counter with something rediculous like "well math doesn't actually exist and heres why "..... etc etc. and then becomes an argument about the existence of math and language and I have to justify my answer by proving that math exists! totally avoiding the essence of the argument witch was that 2+2 does in fact equal 4.